Método de monitoramento radiométrico para de disjuntores de alta tensão.

Abstract

The techniques used to monitor and diagnose circuit breakers currently used by electric companies have some technical limitations, such as an invasive nature, low reliability and difficulty of application. According to statistical data, circuit breakers are one of the faultiest equipment in transmission/distribution systems. Hence, in this research is presented a new radiometric monitoring method for high voltage circuit breakers based on computational routines and the use of printed monopole antennas with bioinspired geometry. The method facilitates the monitoring process and makes it more efficient. The proposed methodology is based on the measurement of electromagnetic signals radiated by the circuit breaker during current interruption operations, in statistical techniques such as boxplot analysis, and a classifier algorithm for data processing and decision making. For the development of the measurement system a broad research was carried out to analyze the spectral characteristics of the signals radiated by circuit breakers, enabling the design of optimized sensors for this application. Printed monopole antennas were designed, manufactured and tested using gain and bandwidth optimization techniques as well as miniaturization techniques, making them suitable for the monitoring of different types of circuit breakers. The carried out experiments generated promising results, allowing the detection of different types of failure, such as high level of contact degradation, mechanical failures in the actuating system, loss of the dielectric characteristics of the extinguishing medium and mechanical failure in the contacts. In laboratory, comparisons with the diagnosis provided by reference techniques indicated a 100% agreement regarding the level of contact degradation. Field experiments were performed on an SF6 circuit breaker used for the switching of a 33 MVAr reactor, attesting the applicability of the technique.